Parvamussium vidalense (Barnard, 1964)
BARNARD, K. H. 1964. Contributions to the knowledge of South African marine Mollusca. Part V. Lamellibranchiata. Annals of the South African Museum, 47 (3): 361-593 [p. 433, figs. 14e-14g]
1964 Cyclopecten vidalensis Barnard, 1964
K. H. Barnard, 1964, figure 14.
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«Left valve only—subcircular, moderately convex, anterior ear larger than posterior ear; concentric growth-lines showing at 0.5 mm. alt., about 10 ribs appear at 1 mm. alt., and intermediaries begin at 2 mm., about 45 ribs (main and intermediary) at margin of shell; ribs slightly stronger than the concentric lamellae, together forming a cancellate sculpture, intersections slightly nodular or squamulose, the latter chiefly on the lateral parts of the shell; earliest part with extremely fine radial striae which later become stronger and clearly visible in the hollows of the lattice sculpture; ears with concentric lamellae. Internally hinge narrow, a small ligament pit, crurae well marked but without ridge or denticle, no radial costae except 2 short costae and a denticle between them anteriorly and posteriorly, margin smooth. Dull buff (opaque).
Length and alt. 7.5, hinge-line (chipped) 4 or 4.5 mm. Off Cape Vidal (Zululand), 80-100 fathoms, one valve (S. Afr. Mus. No. A9495. P.F. coll.). Remarks. Provisionally placed in Cyclopecten; but if this valve is juvenile, older shells might show better developed internal costae, which would indicate removal into another genus.» KEPPEL HARCOURT BARNARD, 1964
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«Distribution and habitat: South Africa, off KwaZulu-Natal. Now also southern Madagascar (new record). Previously only a single left valve (holotype) at -146–183 m. Present left valve dead at -225–282 m.
Remarks: The present specimen from southern Madagascar is morphologically identical to the type specimen. Parvamussium vidalense was provisionally placed in Cyclopecten by Barnard (1964: 433), but developed internal riblets justified placing in Parvamussium.
A close congener from the SW Pacific is Parvamussium araneum Dijkstra, 1991, which differs from by having finer and more closely spaced commarginal lamellae, more delicate radial riblets on the left valve, more spineous sculpture on the intersections, and less-developed internal riblets.» DIJKSTRA, H. H. & P. MAESTRATI. 2015. Pectinoidea (Bivalvia: Propeamussiidae and Cyclochlamydidae) from the southwestern Indian Ocean. African Invertebrates, 56 (3): 585-628, figs. 1-8. [p. 614]
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